If the fixed costs are 10 and the variable costs are Q + 3 per good, and the demand function is given by P + 4Q= 900. Determine :

1)     The expressions for TR, TC, π and AC.

2)    The expressions for MR, MC, Mπ.

a.1- TR= - 4Q² + 900Q , TC= Q² + 2Q +20 , π = -5Q² + 898Q - 20 , AC= Q + 2 + 20/Q

2- MR= -8Q + 900 , MC= 2Q + 2 , Mπ = - 10Q + 898

b.1- TR= - 3Q² + 1000Q , TC= Q² + 2Q +20 , π = -4Q² + 998Q - 20 , AC= Q + 2 + 20/Q

2- MR= -6Q + 1000 , MC= 2Q + 2 , Mπ = - 8Q + 998

c.1- TR= - 4Q² + 1000Q , TC= Q² + 2Q +20 , π = -5Q² + 998Q - 20 , AC= Q + 2 + 20/Q

2- MR= -8Q + 1000 , MC= 2Q + 2 , Mπ = - 10Q + 998

d.1- TR= - 4Q² + 900Q , TC= Q² + 3Q+10 , π = -4Q² + 897Q -10 , AC= Q +3 + 10/Q

2- MR= -8Q +900 , MC= 2Q + 3 , Mπ = - 10Q + 897

The demand and supply function of a certain good are given by

P = - Q_D² – 2Q_D + 78 and P = Q_S² – 6Q_S + 30 .

Calculate the consumer’s surplus at equilibrium..

a. CS= 240

b. CS= 120

c. CS= 216

d. CS=180